Expert: Scott Valentine - 4/4/2008

Question
QUESTION: My client provided me with B&W art and I am uncertain whether the
resolution will be good quality for print. When I open to check image size, it
says the document is 52x69 inches with a resolution of 72 pixels/inch. I only
need to make the image 6x9 inches which when brought into my document
puts it at a size of 270%. (This also confuses me--if the document is 52x69,
why would it need to be blown up to 270% to cover a 6x9"size?) In any case, I
understand that the standard resolution for printing is supposed to be 300.
When I see that this is 72, I wonder if I need to ask my client for the same
image at 300? By the way, it looks great when I print out of my printer full
size. Does this mean that the fact that it is allegedly a 53x69" document size
that the resolution is actually close to 300 for my size purposes? I appreciate
any input you have, Thank you!

ANSWER: Hi Mary,

You should be fine printing the image at 300dpi, which will still keep it around 12" x 16". Printing smaller is almost never a problem, but you may need to do some slight sharpening when making that big of a change. No need to ask for a new image :)

I'm not sure I understand the 270% reading you are getting, but I wouldn't worry too much about it. The best bet is simply to try a test print and see if you like the results. Also, 300dpi is great for photographs, but other artwork and graphics can be printed at lower resolutions and still look fine. Keep in mind the viewing distance is related to the document size and presentation environment, and the resolution you choose will depend on the print method.

Sorry for the delay. If you have further questions, please don't hesitate to ask!

-Scott

---------- FOLLOW-UP ----------

QUESTION: Hi Scott,
Thank you so much for your answer. I may not have been totally clear with my question. I am concerned with ppi. When you say that it should be fine printing at 300 dpi, do you mean that the image resolution stated as 72 is actually closer to 300ppi because it is coming down in size? (Please excuse my ignorance!) I was under the impression before you send an image out for printing to check the resolution--that it should ideally be 300 (at 100%size). Thank you so much for any clarity on this, I really appreciate it.
Sincerely,
Mary

ANSWER: Ah-ha. ppi and dpi are different beasts. ppi (pixels per inch) refers to the screen size, while dpi refers to print resolution. They are similar in concept, but not the same in practice. I'm afraid I muddled things with my description above (I used the wrong terms). In short, ppi is used to tell the printer how many pixels to fit into one inch of printed art. dpi is how many dots of *ink* the printer lays down to make an inch, and is not part of the digital image. You can print higher and higher dpi without changing the size of the image, but changing ppi changes the dimensions on paper.

Here are some great resources that will explain in more detail than I can provide in this forum:

http://www.digicamguides.com/print/ppi-print-size.html

http://photo.net/learn/resize/

If your image is truly set to 72ppi, and the document dimensions are 52"x69", then changing the ppi to 300 (as you do when dragging it to a document set to 300ppi) will reduce the print size to 12.48"x16.56" as you note. You can then use the transform tool to resize it down to fit 6"x9". The actual resolution in ppi won't change at that point - changing the physical size of an image using the transform tool does not affect the ppi, just the physical dimensions.

I hope this clears things up a bit. Please do let me know if I can be of further assistance, and I'm sorry for the confusion!

-Scott

---------- FOLLOW-UP ----------

QUESTION: Thank you Scott!!! That helps me understand better, and now I get where your 12x16 dimension is coming from. Thank you also for the article links. The way I am understanding this now is that yes, this image will have high quality resolution for the size I need to print it at, since it translates to 300ppi at a 12x16" size. My final follow up question (i promise!)--it is not nessisary for me to change the ppi setting for the image, is it? I understand that if I do, it will simply reduce the print size, but I am more comfortable leaving as is. Is it better for me to go ahead and change the ppi, or will it not make a difference either way?

Answer
Hi Mary - I'm having trouble seeing these responses in a timely manner  :P

I do recommend you change the ppi to 300, then when you go to print, use the print dialog (or have the printer set up the RIP) to get the final, smaller size. Changing the ppi is just a set of instructions, and does not change the actual document in any way. You can create a copy if you are concerned, and send that one with all the print instructions to the printer.

No worries about the follow-ups, Mary. I just wish I would get the notifications more promptly!

-Scott